1. Field of the Invention
The present invention relates to a high-density data storage medium using emission of electrons caused by photons, a method of manufacturing the data storage medium, a data storage apparatus, and methods of writing data on and reading and erasing data from the data storage medium.
2. Description of the Related Art
In accordance with the increasing demand for small-sized electronic devices, such as mobile communications terminals or electronic notebooks, development of ultra small-sized high-density data storage media and apparatuses are becoming more necessary. However, it is not easy to manufacture small-sized hard disks and to increase the integration density of flash memories. Therefore, research has been carried out on various techniques of writing data on a data storage medium using a scanning probe. Here, the scanning probe is a probe used for a scanning probe microscope (SPM), such as a scanning tunneling microscope (STM) or an atomic force microscope (AFM).
The data storage medium, on which data can be written using such a scanning probe, can be formed of a ferroelectric material, a ferromagnetic material, a thermoplastic resin, or a thermosetting resin. In particular, a great attention has been paid to a data storage medium formed of a ferroelectric material because of its small-sized domains and ability to quickly change a polarization direction.
Data can be written on a conventional data storage medium using a ferroelectric material by generating an electric field using a voltage applied to a lower electrode and a probe and thus dielectrically polarizing only some part of the data storage medium where the electric field has been generated. However, there is a limit in stably storing data in the data storage medium because of an aging phenomenon and a fatigue phenomenon. Here, the aging phenomenon indicates that as time goes by, such dielectric polarization continues to weaken and finally disappears, and the fatigue phenomenon indicates that as the number of times when data are written on and read from the data storage medium increases, the storage capacity of the data storage medium continues to decrease considerably.
In addition, during writing data on and reading data from the data storage medium using a scanning probe in contact with the data storage medium, the scanning probe and the data storage medium may wear each other out. In order to write data on and read data from the data storage medium using a scanning probe that is not in contact with the data storage medium, a data storage apparatus must be vacuum-packaged, and the vacuum packaging process may complicate the whole data writing and reading processes.